Alpha CB24 invisible leak.....?!

[TommyC]

Hi,

This is my first post on this forum but i've used it for info on a few occasions before which has been really helpful

My current problem is proving tricky to diagnose. Having read through the FAQ I am certain i have a leak on my Central Heating circuit. I have been topping the pressure up around 0.5-1.0 bar every couple of weeks (clearly the heating has been used very little the last few months). There are no visible external leaks anywhere i can see.... (The system is grey Hep2o from about 2-3feet from the boiler. I don't know if this would/could have an effect? or mask a leak maybe?!) Which leads me to think there is an internal leak somewhere. I'm guessing the two common places for internal leakage are the Diverter Valve or Heat Exchanger.

Having recently (12-18 months ago) replaced the Diverter Valve i suspect it is a Heat Exchanger. Is there any way i can narrow the fault diagnosis any further to tell if its the Primary or Hot Water (DHW) Heat Exchanger?

(Boiler is an Alpha CB24)

Many Thanks

Tommy

 

[Agile]

You seem to think that only individual parts can leak! The reality is that most leaks are on the joints.

The FAQ are very helpful but you don't appear to have done the first test to see if the leak is in the heating system or the boiler. Do that and then we will advise you what to look for next.

Tony

 

[nickso]

Remember and change the leaking isolation valves after you perform Agiles test

 

[bellairaphon]

An Alpha boiler that leaks? No way! :-/

 

[TommyC]

You seem to think that only individual parts can leak! The reality is that most leaks are on the joints.

Tony

I see what you're saying..... I've had a good look around everything i can see and there is no evidence of any leaking, components, joints, pipe connectors, everything i have easy access to. I haven't however started pulling up floor boards to inspect hidden joints and connectors.

I am used to working on hydraulic systems where leaks are easy to spot and nitrogen systems where you can use Leak Detection Fluid (Snoop etc). I've experienced 'hidden' leaks in the past inside components, heat exchangers in particular. Judging by the state of the old diverter valve and diaphragm when i replaced them it seemed logical to suspect one of the exchangers, but i'm open to any suggestions....

I must've skipped past the circuit pressure test. I'll give that a try

Cheers

Tommy

 

[dcawkwell]

Most likely a very tiny leak at a radiator given it takes weeks before it needs a top up.
Wouldn't worry. If you only need to top it up every few weeks it isn't uncommon.

Have you checked for a leak at the pressure relief pipe outside?

 

[Agile]

He says two weeks which is too frequent to leave as it will rust the rads if left.

But its still going to evaporate almost as fast as it comes out in warm weather.

But he will know a little more when he has done the first test!

Tony

 

[TommyC]

So, i've read through most of the posts in the FAQ thread AND the Boiler and Central Heating FAQ thread and there appears to be no mention of a pressure test for the CH Circuit.....???!!

Also i'm trying to imagine how this is achieved. I would guess at Isolating it from the boiler, breaking into the system, rigging up a direct reading gauge, pressurising using a separate water feed, and monitoring over time to see the pressure drop off whilst looking for leaks.....

To be honest i'm not sure i have the kit or the time for that....

 

[Homesafe]

A tip that could work is if you could get some cheap aftershave/perfume into the system and smell where it leaks out.
Sounds funny, but will work

 

[bellairaphon]

If you isolate the boiler and mark where the dial is. If you leave it overnight and check it in the morning you will see if the guage has fallen. If not then you can say your leak is on the heating.

Nath

 

[Boilerman2]

I assume that you have already de-pressurised your system and checked the air charge in the expansion vessel?? pump it up to 1-00 bar if low with the PRV open, and have you checked the PRV for let by (turning off the F&R isolation valves as previously advised will assist with this)